    :comparator (fn [i1 i2] (compare i2 i1))})
 
 (deftask collection
-  "Render collection files"
+  "Render single file for a collection of entries
+  The symbol supplied as `renderer` should resolve to a function
+  which will be called with a map containing the following keys:
+   - `:meta`, global perun metadata
+   - `:entries`, all entries
+
+  Entries can optionally be filtered by supplying a function
+  to the `filterer` option.
+
+  The `sortby` and `groupby` functions can be used for ordering entries
+  before rendering as well as rendering groups of entries to different pages."
   [o out-dir    OUTDIR     str  "the output directory"
    r renderer   RENDERER   sym  "page renderer (fully qualified symbol resolving to a function)"
-   _ filterer   FILTER     code "filter function"
-   s sortby     SORTBY     code "sort by function"
-   g groupby    GROUPBY    code "group posts by function, keys will be used as filenames where posts (values) will be rendered"
+   _ filterer   FILTER     code "predicate to use for selecting entries (default: `:content`)"
+   s sortby     SORTBY     code "sort entries by function"
+   g groupby    GROUPBY    code "group posts by function, keys are filenames, values are to-be-rendered entries"
    c comparator COMPARATOR code "sort by comparator function"
    p page       PAGE       str  "collection result page path"]
   (let [pods      (wrap-pool (pod/pod-pool (boot/get-env)))

(deftask rss
  "Generate RSS feed"
  [f filename    FILENAME    str  "generated RSS feed filename"
   _ filterer    FILTER      code "filter function"
   o target      OUTDIR      str  "the output directory"
   t title       TITLE       str  "feed title"
   p description DESCRIPTION str  "feed description"


   Make files permalinked. E.x. about.html will become about/index.html"
  [p permalink-fn PERMALINKFN code "function to build permalink from TmpFile metadata"
   _ filterer     FILTER      code "predicate to use for selecting entries (default: `identity`)"]
  (boot/with-pre-wrap fileset
    (let [options       (merge +permalink-defaults+ *opts*)
          files         (filter (:filterer options) (perun/get-meta fileset))
